Grabby Aliens

The Grabby Aliens model is an attempt to describe the development of alien civilizations across outer space. It postulates that some aliens are ‘grabby’: their civilization rapidly expands, and they prevent other beings like themselves from emerging within their volume. Over time, such civilizations would naturally predominate over the whole universe, leading to consequences for humanity’s place in the cosmos that we explore in our paper.


2021/02/01: A Simple Model of Grabby Aliens (preprint), by Robin Hanson, Daniel Martin, Calvin McCarter, and Jonathan Paulson.

Model visualisation
Open-source code

Robin’s original blog posts

2020/12/21: How Far To Grabby Aliens? Part 1.
2020/12/21: How Far To Grabby Aliens? Part 2.
2021/01/03: Try-Menu-Combo Filter Steps
2021/01/08: Why We Can’t See Grabby Aliens
2021/02/02: An Adventure
2021/02/03: Humans Are Early

Presentations and interviews

2020/12/28: Robin’s appearance on SciFuture
2021/02/09: A Simple Model of Grabby Aliens, Foresight Institute

Coverage and discussion

2021/01/30: Shtetl-Optimized
2021/01/30: Reddit
2021/01/31: Hacker News
2021/02/03: Marginal Revolution